As is known, ships' bells are sounded on both the half and the full hour with a pattern of strokes recurring after a 4-hour operating period or "watch". The number of strokes is odd on the half hour and even (i.e. one, two, three or four stroke pairs) on the full hour. The separation of the stroke pairs on the 2nd, 3rd and 4th hour is greater than the interval between the strokes of any pair; on the preceding half hour, similarly, the stroke pair or pairs are followed after a larger interval by a single stroke.
In earlier times, clocks of this type were widely used aboard naval vessels and merchant ships for the purpose of giving chronometric information by acoustic signaling to the seamen on duty. The half-hour timing stems from the original use of 30-minute sandglasses for this purpose. With the 24-hour day divided into six 4-hour watches, the number of bells generally conforms to the following program:
______________________________________ Midnight (noon) : 8 bells (beginning of watch) 0030 hours (1230 hours) : 1 bell 0100 hours (1300 hours) : 2 bells 0200 hours (1400 hours) : 4 bells 0230 hours (1430 hours) : 5 bells 0300 hours (1500 hours) : 6 bells 0330 hours (1530 hours) : 7 bells 0400 hours (1600 hours) : 8 bells (change of watch) 0430 hours (1630 hours) : 1 bell (beginning of new watch) and so forth. ______________________________________
Although so-called ships' clocks are no longer in common use aboard naval and commercial vessels, they are popular as timepieces on pleasure boats and even in dwellings.
A variety of electronic circuits have already been proposed for the operation of a striker mechanism in response to periodic switch closures by an associated clockwork. See, for example, U.S. Pat. Nos. 3,689,919 and 3,210,913, the latter referring particularly to a ship's clock.